Open YouTube and find the video you want to download
If available, click the Download button under the video (or in the video menu)
Choose the desired quality/format and confirm the download
If there is no Download option, use YouTube Premium’s offline feature in the YouTube app
Open the video in the YouTube app while logged in to a YouTube Premium account
Tap Download and select the quality
Open the YouTube app’s Library/Downloads to play offline
If you use a third-party tool, download only videos that you have rights to download and follow the tool’s instructions